LOCATION STEPOFF IDEstablished Series
TAXONOMIC CLASS: Medial over loamy, amorphic over isotic, frigid Typic Udivitrands
TYPICAL PEDON: Stepoff medial loam, shrubby alder patch, on a 35 percent slope at 4,550 feet elevation on a south aspect. When the soil was described on October 18, 1994, it was moist throughout. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 2 inches; undecomposed leaves, twigs and grass. (0.5 to 2 inches thick)
Oe--2 to 3 inches; slightly decomposed leaves, twigs and grass. (0 to 1 inch thick)
A--3 to 8 inches; dark yellowish brown (10YR 4/4) medial loam, very dark brown (10YR 2/2) moist; weak fine and medium granular structure; very soft, very friable, nonsticky and slightly plastic; many very fine and fine roots throughout; many very fine and fine irregular pores; 2 percent fine, rounded iron-manganese concretions; 1 percent fine mica flakes; 5 percent gravel; very strongly acid (pH 5.0); clear smooth boundary. (5 to 18 inches thick)
Bw1--8 to 15 inches; yellowish brown (10YR 5/4) medial loam, dark yellowish brown (10YR 3/4) moist; weak fine and medium subangular blocky structure parting to moderate fine and medium granular; soft, very friable, slightly sticky and slightly plastic; many very fine, fine, medium and coarse roots throughout; many very fine and fine irregular pores; 3 percent, fine, rounded iron-manganese concretions; 2 percent fine mica flakes; 5 percent gravel; very strongly acid (pH 4.7); clear smooth boundary.
Bw2--15 to 24 inches; yellowish brown (10YR 5/4) medial loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine, fine and medium and common coarse roots throughout; many very fine and fine irregular pores; 2 percent fine, rounded iron-manganese concretions; 2 percent fine mica flakes; 10 percent gravel; very strongly acid (pH 4.7); clear smooth boundary. (Bw horizons 9 to 17 inches thick)
2Bw3--24 to 32 inches; yellowish brown (10YR 5/4) gravelly loam, dark yellowish brown (10YR 4/4) moist; moderate fine and medium subangular blocky structure; soft, friable, slightly sticky and slightly plastic; common very fine, fine and medium and few coarse roots throughout; common very fine and fine irregular and few very fine tubular pores; 4 percent fine mica flakes; 15 percent gravel; very strongly acid (pH 4.6); clear wavy boundary.
2Bw4--32 to 38 inches; yellowish brown (10YR 5/6) gravelly loam, dark yellowish brown (10YR 3/6) moist; moderate medium and coarse subangular blocky structure; soft, friable, slightly sticky and slightly plastic; common very fine, fine and medium, and few coarse roots on faces of peds, common very fine roots throughout; common very fine and fine irregular pores; 3 percent fine mica flakes; 15 percent gravel; very strongly acid (pH 4.7); gradual wavy boundary.
2Bw5--38 to 46 inches; yellowish brown (10YR 5/4) gravelly loam, dark yellowish brown (10YR 4/4) moist; moderate medium and coarse subangular blocky structure; soft, friable, slightly sticky and slightly plastic; common very fine, fine and medium roots on faces of peds and few very fine roots throughout; common very fine and fine irregular and few very fine tubular pores; 3 percent fine mica flakes; 10 percent gravel and 5 percent cobbles; very strongly acid (pH 4.8); clear wavy boundary. (2Bw horizons 15 to 24 inches thick)
2C--46 to 63 inches; light yellowish brown (10YR 6/4) very cobbly loam, yellowish brown (10YR 5/6) moist; moderate fine and medium subangular blocky structure; soft, friable, slightly sticky and slightly plastic; few very fine roots throughout; few very fine irregular pores; 2 percent fine mica flakes; 30 percent gravel and 25 percent cobbles; very strongly acid (pH 4.8).
TYPE LOCATION: Clearwater County, Idaho; about 18 miles north of Headquarters, Idaho, about 850 feet north and 200 feet east of the southwest corner of section 13, T41N, R5E; Latitude - 46 degrees, 53 minutes, 37 seconds North; Longitude - 115 degrees, 47 minutes, 01 second West; USGS Little Goat Mountain Quadrangle.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 39 to 45 degrees F. (Frigid soil temperature regime)
Soil moisture control section - not dry for 45 consecutive days between June and October (Udic moisture regime)
Thickness of volcanic ash mantle - 18 to 25 inches
Volcanic glass content - 15 to 50 percent
Acid-oxalate extractable Al + 1/2 Fe - 1.3 to 2.7 percent
Phosphorus retention - 55 to 95 percent
15 bar water content - 8 to 33 percent on air dried samples (weighted average of 15 bar water content for all horizons with andic soil properties is greater than 15 percent)
A horizon
Hue - 7.5YR or 10YR moist
Value - 3 or 4 dry, 2 or 3 moist
Chroma - 3 to 6 dry, 1 to 3 moist
Texture -Medl-SIL , Medl-L
Clay content - 8 to 12 percent
Mica content - 0 to 2 percent
Rock fragments - 2 to 10 percent gravel
Reaction - extremely acid or very strongly acid
Bulk density - 0.65 to 0.90 g/cc
Bw horizons (AB horizons when present)
Hue - 7.5YR or 10YR moist
Value - 5 to 7 dry, 2.5 to 5 moist
Chroma - 4 to 6 dry, 2 to 6 moist
Texture - Medl-SIL , Medl-L or CB-Medl-SIL
Clay content - 8 to 18 percent
Mica content - 1 to 6 percent
Rock fragments - 0 to 10 percent gravel, 0 to 10 percent cobbles, 2 to 20 percent total rock fragments
Reaction - extremely acid to strongly acid
Bulk density - 0.65 to 1.00 g/cc
2Bw horizons
Hue - 7.5YR or 10YR moist
Value - 5 to 7 dry, 3 to 5 moist
Chroma - 4 to 6 dry, 3 to 6 moist
Texture - L, LCOS, GR-L or GRV-SL
Clay content - 14 to 22 percent
Mica content - 0 to 5 percent
Rock fragments - 2 to 35 percent gravel, 0 to 10 percent cobbles, 10 to 40 percent total rock fragments
Reaction - very strongly acid to strongly acid
2C horizon
Hue - 7.5YR or 10YR moist
Value - 5 to 8 dry, 3 to 7 moist
Chroma - 3 to 6 dry, 4 to 6 moist
Texture - L, SL, COS, CBV-L, GRV-L or GRV-LS
Clay content - 2 to 18 percent
Mica content - 1 to 10 percent
Rock fragments - 5 to 30 percent gravel, 0 to 25 percent cobble, 5 to 55 percent total rock fragments
Reaction - very strongly acid to strongly acid
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Stepoff soils are on mountain slopes at elevations of 2,000 to 4,900 feet. They formed in colluvium and residuum from granitic and metamorphic rock with a mantle of volcanic ash on slopes of 15 to 65 percent. The average annual temperature ranges from 38 to 44 degrees F. The average annual precipitation is 40 to 60 inches and the frost free season is 50 to 110 days (9 years in 10 to 1 year in 10 respectively).
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bouldercreek, Brodeer, Flumecreek, Rettig and Township soils. Brodeer soils are on mountain slopes and have an argillic horizon. Bouldercreek, Flumecreek and Township soils are on mountain slopes and are skeletal. Rettig soils are on mountain slopes and are paramicaceous.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability and slow to moderate runoff.
USE AND VEGETATION: These soils are used for wildlife habitat and watershed. Potential natural vegetation is sitka alder with an understory of miners lettuce, lady fern, wild ginger, bracken fern, false bugbane, arrowleaf groundsel, trillium, coolwort foamflower, and pioneer violet.
DISTRIBUTION AND EXTENT: North central Idaho, Stepoff soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Clearwater County, Idaho, 2003.
REMARKS: Diagnostic horizons and other features recognized in this pedon are:
Volcanic ash mantle - The zone from the mineral soil surface to 24 inches. (A, Bw1 and Bw2 horizons)
Ochric epipedon - The zone from the mineral soil surface to 8 inches. (A horizon)
Cambic horizon - The zone from 8 to 46 inches. (Bw1, Bw2, 2Bw3, 2Bw4, and 2Bw5 horizons)
Particle-size control section - The zone from the mineral soil surface to 43 inches. (A, Bw1, Bw2, 2Bw3, 2Bw4 and part of the 2Bw5 horizon)
The ranges of value listed under the Range in Characteristics for Bulk density, Volcanic glass content, Acid-oxalate AL+ 1/2 Fe, Phosphorus retention, and 15 bar water retention are estimates only.